The present invention generally relates to a storage apparatus and a storage apparatus control method, and in particular can be suitably employed for balancing the load from a host system to a logical unit.
In the recent trend of storage consolidation with Web servers and contents distribution, storage apparatuses are shared based on a plurality of applications or contents, and systems unable to anticipate the load status against the logical volume of the storage apparatus based on the respective applications and the like are increasing.
Under these circumstances, in recent years, in order to improve the throughput of the storage apparatus, a method has been proposed for improving the throughput by storing data of a certain logical unit in another logical unit so as to enable the referral from a logical unit storing much information (refer to Japanese Patent Laid-Open Publication No. 2003-241905).
Further proposed is a method for balancing the load from a host by measuring the load status of a logical volume as a logical storage extent set to be provided by a physical disk drive in a storage apparatus, copying the contents of a logical volume set in a physical volume to a logical volume set in a backup physical volume when the load is determined to be high based on the measurement results, and providing to a host system a copied logical volume set in a backup physical volume and a logical volume set in a physical volume of a copy source as one virtual logical volume. Moreover, this method seeks to balance the load by accessing a logical volume with the smallest load among the virtual logical volumes during the reading of data from the host system (refer to Japanese Patent Laid-Open Publication No. 2006-053601).
According to this method, it is possible to provide a storage apparatus capable of performing dynamic load balancing or performance acceleration to a peak performance request that is unable to anticipate the time series variation of Web servers and contents distribution.